Sealing composition



- practice with some battery manu Patented Aug. 12, 1930 UNITED STATESPATENT OFFICE IIAUCHLIN M. GUBBIE,

OFLAKEWOOD, OHIO, ASSIGNOR TO NATIONAL CARBON 60., INCL, AUCOBPOBATIONYORK I SEALING COMPOSITION Application filed May 10,

This invention relates to improvements in thermoplastic compositions'for use in sealing dry cells and dry cell batteries. A compositionwhich has been rather generally used to seal dr cells-and dry cellbatteries is a mixture o rosin and a mineral filler. Usually smallamounts of lime,for strengthening purposes, and coloring matter are alsopresent. Seals of this composition show a pronounced 1 tendency to crackwhen subjected to sudden and extreme temperature changes. Such crackingis accentuated when lime is present and particularly whensuch seals arepoured upon an asphaltic sub-seal base as is the f acturers. The presentinvention hasfor an object the production of a seal which ischaracterized by toughness and ability to withstand wide 1 and suddentemperature changes wlthout 2o cracking, even under the specialconditions above mentioned. Another object of the invention is toprovide a sealing composition 7 having greater fluidity at a giventemperature, thus permitting the pouring operation to be more easilycontrolled or to be carried on at a lower temperature. A further objectof the invention is to provide a sealing material which wets the brassterminals and other metallic portions of the cell with which it comesinto contact and adheres more readily and firmly thereto than has beenthe case with the sealing compositions heretofore used. Other objectsandadvantages of the invention will appear from the appended descri tionand drawing.

The figure of drawing is a perspective view of a battery partly brokenaway.

' According to the present inventlon small percentages of a non-dryingoil or a poly- 'hydricalcohol or both, and with or without certainadditionalmaterials hereinafter to be described, are added to therosin-mlneral filler composition. Either vegetable or'mineral non-dryingoils may be used, although the former arepreferred. A vegetable oil"which has been found especially suitable for the purposes of the presentinvention isv castor oil. Other non-drying vegetable oils which can beused with satisfactory results are olive oil, peanut oil and palm oil.Examtion containing approximately 50% 1927. Serial No. 190,280.

ples of mineral oils'which may be used are paraflin oils such as strawparaffin oil. Of the polyhydric alcohols, glycerine has -been found tobe most suitable for the purposes of this invention although others maybe used.

The amounts of addition materials which are requlred to effect thedesired improvements vary somewhat with the proportions of rosin andmineral filler used, and particu larly with respect to the amountof'lime used for strengthening purposes. In general the amount of oil orglycerine addition should not exceed about 3% by weight of the sealcomposition, and preferably is varied in direct proportion to the amountof lime present in the composition.

For a rosin-mineral filler sealcomposition containing a relativelyhigh-lime content, namely 1%, and with the proportions of rosin andmineral filler so controlled as to give a seal which is characterized byhigh strength and ability to resist bulging or rupture,-aside from itstendency to crack be: cause of temperature changes,-when subjected tostresses such as are due to the internal pressure created by gasesgenerated within the dry cells of the battery, castor oil additionsranging from 1% to 2.25% have been found to give highly satisfactoryresults. Good results may also be obtained by substi tultlng glycerinein part or wholly for castor o1 The following comparative resultsindicate the improvement which has been obtainteddby the use ofadditions of the class descr1 e Eaiample No. 1

One lot of batteries sealed with a composirosin 3 6% sand, 10% fibrousasbestos, and 1% l1me,-w 1th the balance coloring matter, was placed 1ncold storage at 0 0., and observed for cracking of the seal. After threedays, 21% of the batteries showed cracks in the seal and after eightdays, the seal of 25% of the batteries had'cracked.

Another lot of batteries similar in every respect except that 1.5% ofcastor oil was added to the seal composition, was subjected to only 8%requiring retorching.

identical cold storage conditions and showed properties ofthe seal tothe desired extent nocracking of theseal at the end of fourand also toimpart requisite strength. In ad-.

' dition to the above mentioned improved teen days in cold storage. I

The castor oil-treated seal also showed infproperties which arepossessed by treated provement's in other respects and particularsealsas compared with untreated seal comly as to pouringfproperties, freedomfrom positions, itis to be noted that the molten pits and air bubbles,The untreated seal treated seal much more readily wets the-brass waspoured with some difliculty and was terminals and other metallicportions of the characterized by the presence of bubblesgwith cells withwhich it comes in contact than does 24% of the batteries requiringretorching, the untreated seal composition, thus insurwhereas the castoroil-treated seal poured .ing more perfect sealing at these surfaces of Ievenly and well at a somewhat lower tern contact. perature and formed asmooth surface with notes a battery box or casing which may be 'made ofcardboard, wood orother suitable Ewampl NO- 2 material. Cells 2 arearranged in the casing .Two lots ofhatteriessealed with approxiand arepreferably compactly assembled in mately' the same rosin-mineral fillercomthree rows offive cells each. Connectors 3 position as specified inExample No. 1, except join the cells in series and externalterminalsthat the lime content was only approxi- 4. and 5 are provided.macely'0.5%, and the castor oil content of When the cells are properlyassembled in Referring to sit drawing, numeral 1 dethe treated lot was0.5%, when subjected to the casing, an insulating asphaltic sealing coldstorage conditions, showed similar imcompound is made fluid byheatingand is provement in favor of the'oil-treated seal. poure'dabout thecells, preferably in quan- Of the lot containing untreated seal, theseal tity suflicient to completely embed them and, on 3% cracked inseven vdays, and 12.5% in to extend over their tops to form a layer offourteen days. None of the lot using castor substantial thicknessthereon, as indicated at oil-treated seal showed cracks at the end of 6.I After the asphaltic sub-seal 6 is solidified.

fourteen days in cold storage. Better finish a finish -layer 7 ofsealing material composi:

of the seal and control of thepouring operation of the'kind morespecifically described tion was obtained with the treated seal. above ispoured" over this1 sub-seal to fill the casing su stantially to t e top.

. I m 3 I The' invention is shown in the drawing as Another lot ofbatteries sealed wlth a applied to a conventional form of batteryrosin-mineral filler composition containing used in radio'communication.It is to be approximately 0.5% of lime and to which understood, however,that it is not limited in had been added 1.1% anhydrous Z1110! 8111-application to this type ofbatteryand may phate and 0.5% glycerine, wasplaced in COId be applied in sealing other types of batteries storagefor ten days 'and compared with alot as well as single cells. sealedwith amaterial similar incomposition It, i l o t 'b und t d th t variousexcept h 0I1t8i118d "noi ph modifications may be made in theroporglycerine addition. :At tlie end of ten days tions'and kinds ofmaterials used in orming 17.5% of the untreated lot showed cracks as therosin-mineral fille o iti which compared with 4% of thetreated seals.forms the basefor my new composition. For When zinc sulphate is used inaddltlon example, while rosin has been specified above,

oil or glycerine the amount of sulphate adde it will be understood thatequivalent natural preferably should beabout equal in moleclb andartificial resins may be substituted.

lar proportions to the lime content 20f Also, various othermaterialsthanthose inthe seal composition. Other addition madicated may comprise themineral filler comterials which may be added in conjunction nt, withglycerine or a non-drying oil are various Wh t I l i metallic soaps suchas lead tungate, lead 1. A battery seal composition consisting linoleateor lead resinate. These material principally of rosin and a mineralfiller and v as well as zinc sulphate,

serve to strengthen including minor proportions of a non-drying the sealand are preferably introduced with t bh il d lime i the glycerine orother oil addition when the 2. A battery seal composition consistingrosin-mineral .filler composition used is one principally of rosin and amineral filler and which would otherwise be characterized; by containingminorproportions of castor oil relatively low strength. Forsuch relatveand lime.

ly low strength seal compositions contaimng up to approximately 0.5%-lime, molec principally 'of rosin and a mineral filler, and PIOPOIUOIIS;of anhydrous zinc sulp containing minor-proportions of &-non-dryequivalent strengthening addition, and from i v getable oil,glycerine,-and lime. 0.25% to 1.10% glycerine and/or non-drying 4. Abattery seal composition containing oil are sufiicient to improve thenon-cracking principally rosin and a mineral filler, up to 139 1% oflime, and up to 3% of a non-drying vegetable oil.

5. A battery seal composition containing approximately .5% to 1% lime,from about .25 5 to 3% of at least one of the following nondryingsubstances: a-polyhydric alcohol, a non-drying oilyand the remainderprincipally rosin and mineral filler.

6. A battery seal composition containing m approximately .5% to 1% lime,from 25% to 3% of at least one of the following nondrying substancesglycerine, a vegetable nondrying oil; and the remainder principallyrosin.

7. A battery seal composition containing approximately .5% to 1% lime,from .25% to 3% of at least one of the following non-drying' substances:glycerine, castor oil; and the remainder principally rosin.

8. A battery seal composition containing approximately 95% of rosin andmineral filler, up to about 1% lime, and up to about 3% of a polyhyolricalcohol, with the balance principally coloring matter.

9. A battery seal composition consisting principally of rosin and amineral filler, and including minor proportions of a polyhydric alcohol,lime and anhydrous zinc sulphate.

10. A battery seal composition containing :o principally rosin and amineral filler, up to 0.5% lime, up to 1.1% anhydrous zinc sul phate,and upto 1.1% glycerine.

In testimony whereof. I afiix my signature.

\ LAUCI ILIN M. CURRIE.

